Tung oil is the favorite finish of boat builders to protect their teak decks. It penetrates wood fibers and results in a deep, lustrous finish that brings out the grain and character of the wood.

Boiled linseed oil tends to darken wood even more. Linseed oil is mixed with the turpentine to increase penetration of the finish into the wood. So much for the patina of aged teak.

Or there's Watco Danish oil (Fig. 2). It has a little varnish in it, so you get the look of oil with the protection of a polyurethane. You can control the level of shine by adding more coats.